A transfer device refers to a device that can be used in a mass transfer or a heat transfer application. The transfer device when used for mass transfer applications is referred to as a contactor, and when used for heat transfer applications, a heat exchanger.
A contactor is a mass transfer device that removes or adds a material to a fluid. Contactors may be used to remove or add gas to a fluid stream. Such devices are commercially available, for example, see LIQUI-CEL.RTM. contactor offered by CELGARD LLC, of Charlotte, N.C. The LIQUI-CEL contactor is assembled from several pieces that are sealed with a plurality of O-rings and then are mechanically fastened (e.g., clamped) together. This device works well, however, increased demand for these contactors requires that improvements be investigated and utilized. For example, elimination of the O-rings and clamps would be a savings in cost and assembly time and improve long term durability. On the other hand, the mere seal welding of the end caps to the shell, while eliminating the clamps, does not eliminate the O-rings, and therefore does not decrease cost and assembly time and may not improve long term operability. Additionally, contactor components (e.g., shell, end cap, center tube, microporous membranes and potting), are made from dissimilar materials that make joining a difficult problem. Furthermore, the external components are typically made of metal which increases the weight of the device.
A heat exchanger is a heat transfer device that removes or adds heat to a fluid. Heat exchangers, contemplated by the instant invention, are used in applications where temperatures must be below the softening point of the thermoplastic materials used in the device. One such application is in medical devices where fluids must be around body temperature. For example, in medical devices used in open heart surgeries, blood is passed outside the body, loses heat, and before re-entry must be warmed to body temperature. Heat exchangers used in this application are typically made of metal. While functionally they operate well, they pose a disposal problem because they can not be incinerated. On the other hand, a completely thermoplastic device can be incinerated.
Accordingly, there is a need for improved transfer devices and systems for manufacturing them.